1. Field of the Invention
The present invention relates to a portable data collection device (and method) for reading fluorescent indicia, and particularly to, a portable data collection device having a fluorescent imaging mode for reading media bearing fluorescent indicia, and a non-fluorescent imaging mode for capturing digital color images and aiming the device at indicia. The device in non-fluorescent imaging mode is also capable of operating as a digital camera for displaying and storing captured digital images, and for reading of non-fluorescent indicia.
2. Background of the Invention
Portable data collection devices are widely used in factories, warehouses, package delivery services, and retail stores for reading information such as barcodes on media, such as packages for inventory control, tracking, or production control. These collection devices use scanners or readers often having a CCD array for capturing an image and processing either one or two-dimensional barcodes in visible light. Examples of the use of a CCD array in a barcode reader are shown in U.S. Pat. Nos. 5,892,971, 5,414,251, and 5,591,952.
Recently, barcodes and other indicia are being used which are of an ink that fluoresces when illuminated by radiation having a particular excitation wavelength or range of excitation wavelengths, such as light in the ultraviolet spectrum. Barcodes that fluoresce are referred herein as fluorescent barcodes. Fluorescent particles may also be embedded in media, such as currency, stock certificates, or bank notes for security purposes. When the fluorescent ink is illuminated at the excitation wavelength, the ink emits light or radiation of a different fluorescence wavelength. For example, the United States Postal Service using identification tag bar code on mail using ink that fluoresces when illuminated by radiation in the ultraviolet range of the electromagnetic spectrum. To read fluorescent barcodes or other indicia, it is necessary to have a reader that can image a pattern of fluorescent illumination emitted by such indicia. In some circumstances, reading may be provided by measuring the amount of fluorescent illumination emitted from a density of fluorescent particles in media. Typical CCD based barcode readers are not capable of imaging fluorescent barcodes as they lack capability of illumination in the excitation wavelength required for imaging light at a fluorescent wavelength.
U.S. Pat. No. 6,123,263 describes a portable dataform reader for reading fluorescent dataforms, such as barcodes. The reader includes an illumination assembly having a flash tube strobing illumination source focused through an ultraviolet light filter for strobing ultraviolet light. A CCD array in the reader has an exposure time matched to the energization time of the flash tube strobing to capture image frames of fluorescent light of a dataform. Circuitry in the reader provides for decoding of the gray scale values of captured image frames, until the dataform is successfully decoded. Multiple strobing cycles are used to provide multiple captured image frames until a frame having a dataform is successful decoded. Each captured image of the dataform represents a xe2x80x9cnegativexe2x80x9d of the dataform pattern. The processing of a captured image uses a binarizaion algorithm to identify binary values corresponding to the imaged dataform. The device uses visible light targeting LEDs to generate a cross-hair. The targeting LEDs are alternatively energized with the flash tube strobing illumination to avoid image distortion in captured images.
The dataform reader of U.S. Pat. No. 6,123,263 is limited to the capture of fluorescent dataforms using a gray scale CCD and does not provide for color digital imaging such as on a display, like a typical digital color camera, or storage of color digital images. Further, no mechanism is provided for automatically focusing an imaged dataform on the CCD of the reader, as the distance between the CCD and optics are fixed, thereby providing a limited range where the best focus of a dataform image will occur by such optics. The ability of the reader to capture a dataform with sufficient sharpness for decoding when the dataform image would be hindered if the image were not in focus on the CCD. Further, high usage of a flash strobe tube in work environments will cause the flash strobe tube to have a short lifetime, thus necessitating frequent replacement. However, replacement of the flash tube is made difficult due to it being located within the dataform reader. Thus, replacement of the flash tube cannot readily be performed and requires a skilled technician. Further, the duration of ultraviolet light illumination for each capture image cycle is fixed, and not adjustable in response to the amount of received light, which can negatively effect the quality of images on the CCD.
Other portable devices may use pulsed light to read fluorescent indicia, such as described in U.S. Pat. No. 6,184,534, which uses light emitting diodes (LEDs) to generate light that produces fluorescent emission from indicia and images the indicia on a CCD array.
Although typical digital cameras provide for capturing images for display and storage in memory, they do not have indicia decoding technology, or have the ability to provide for illumination and decoding fluorescent indicia.
Accordingly, it is the principal object of the present invention to provide an improved portable data collection device for reading fluorescent indicia that overcomes the drawbacks of the prior art.
It is another object of the present invention to provide an improved portable data collection device for reading fluorescent indicia with a single flash of light having sufficient illumination.
It is still another object of the present invention to provide an improved portable data collection device having a fluorescent imaging mode for reading media bearing fluorescent barcodes or patterns, and a non-fluorescent imaging mode for capturing digital color images and displaying, transmitting, and/or storing images in memory.
It is a further object of the present invention to provide an improved portable data collection device for reading fluorescent indicia having an automatic focusing mechanism.
It is still a further object of the present invention to provide an improved portable data collection device for reading fluorescent indicia which has a replaceable flash module.
Another object of the present invention is to provide an improved portable data collection device for reading fluorescent indicia having an image capture module mounted for pivotal movement.
It is a further object of the present invention to provide an improved portable data collection device for reading fluorescent indicia having multiple white light sources for providing illumination needed for automatic focusing to allow imaging in dim ambient light.
Yet a further object of the present invention is to provide an improved portable data collection device for reading fluorescent indicia which has laser sources for targeting the device for imaging indicia without effecting the quality of images.
A still further object of the present invention is to provide an improved portable data collection device capable of audio sound recording and playback, and a touch screen display for user interface.
It is a further object of the present invention to provide an improved portable data collection device for reading fluorescent indicia having a pivotable image capture module and a user replaceable flash module in the image capture module which has circuitry to enable safe handling if the flash module is charged (or partially charged) when removed.
Briefly described, a portable data collection device embodying the invention includes a housing having a pivotable image capture module. The image capture module includes an adjustable aperture and at least one detector array, such as a color CCD array, for imaging light received through the aperture, and a removable flash module capable of providing light in the excitation wavelength(s) of indicia. Optics, such as a lens, in the image capture module focus light received through the aperture onto the detector array, in which the detector array is mounted in a focusing mechanism which is capable of moving the detector array with respect to the optics to adjust the focus of an image onto the detector array. In the adjustable aperture is an iris wheel having multiple selectable positions of openings of different diameters or a light block in the path of the light to the detector array. A light sensor or photocell, such as a photodiode, coupled to an integrator, in the image capture module measures the amount of ambient light. A programmed controller, such as a microprocessor, is provided in the housing which operates responsive to a user interface, such as buttons, keys, or a touch screen, to capture images and decode imaged indicia or capture color digital images in the memory of the device. A display on the housing shows images received by the detector array in a non-fluorescent imaging mode to target indicia to be imaged and decoded, where the controller provides automatic focus by processing images received by the detector array to detect when the image is in focus and controls the focus mechanism to change the focal distance between the detector array and the lens until a focused (sharp) image is detected. In response to user actuation via the user interface, the controller energizes the flash module to emit light, including the excitation wavelength(s) to enable the indicia to fluoresce, and the detector array receives fluorescent light to capture an image frame of the indicia. Auto exposure circuitry determines the duration of light from the flash module in accordance with the amount of ambient light measured by the light sensor. The indicia captured in the image frame is decoded by the controller to provide data representative of the indicia. The user or controller may set the iris wheel in non-fluorescent imaging mode to provide a proper amount of light received by the detector array. The iris wheel of the adjustable aperture may have in one of the openings an optional filter to pass light of fluoresced (spectra) wavelength(s) of the fluoresced indicia, in which during fluorescent imaging, the iris wheel is positioned such that light is received through the filter.
Multiple white light sources, such as LEDs, may be provided on the image capture module to provide light needed for automatic focusing and target illumination in low ambient light. Further, two laser sources may be provided on the image capture module to emit light to enable targeting of the image capture module with respect to indicia. Such laser sources may be used when the display is not used for targeting the image capture module.
The controller operates in response to an application program stored in memory in the housing. A host computer can communicate with the device, such as to receive decoded indicia or to replace the application program with a different program to enable different functionality of the device.
The term indicia referred to herein are one or two-dimensional barcodes, patterns, or other graphics, characters or symbols.